1. Field of the Invention
The present invention relates to a sealing member, a toner conveying device and an image forming apparatus.
2. Description of the Related Art
Conventional electrophotographic image forming apparatuses, such as copiers, printers, and facsimiles, form an electrostatic latent image by: applying an electric charge to the surface of a photoconductor serving as an image bearer to charge the surface; and irradiating the charged portion with optical image information, such as document reflected light and a laser beam, to expose the charged portion. The image forming apparatuses cause toner supplied from a developing device to adhere to the electrostatic latent image, thereby forming a toner image on the photoconductor. After transferring the toner image onto a recording medium with a transfer device, the image forming apparatuses apply heat and pressure to the recording medium with a fixing device, thereby fixing the toner image. Subsequently, the image forming apparatuses eject the recording medium outside thereof. Foreign matter, such as untransferred toner, is left on the surface of the photoconductor after the toner is transferred onto the recording medium. To address this, the image forming apparatuses remove the foreign matter with a cleaning device or the like and prepare for the next image formation process.
The cleaning device collects the untransferred toner (approximately 5% to 20% of the amount of the toner caused to adhere by a developing unit) left after the transfer out of the toner image formed on the photoconductor. A blade cleaning system is typically used as a cleaning unit. The blade cleaning system removes untransferred toner by causing an edge of a cleaning blade made of an elastic body, such as rubber, to abut on a cleaning target surface of a photoconductor. The untransferred toner removed by the cleaning blade is conveyed in the longitudinal direction of the cleaning device with a collecting screw or the like provided to the cleaning device. The untransferred toner is then conveyed and discharged to the outside from a collected toner discharge port formed on an end. The collected toner discharged outside the cleaning device is conveyed through a collected toner path and is transmitted to a waste toner collection bottle or the like as waste toner. Alternatively, to reduce the amount of toner consumption, the collected toner is returned to the developing device and is reused as recycled toner. The collected toner discharged from the collected toner discharge port formed on an end in the longitudinal direction of the cleaning device is conveyed to a collected toner introduction port (also serving as a new toner introduction port) formed on an end (end on the same side) in the longitudinal direction of the developing device. To convey the collected toner in this manner, a toner conveyance relay device is required serving as a relay unit that connects the collected toner discharge port and the collected toner introduction port.
The toner conveyance relay device includes a collected toner introduction port and a collected toner discharge opening. The collected toner introduction port communicates with the collected toner discharge port of the cleaning device to introduce the collected toner. The collected toner discharge opening communicates with the collected toner introduction port of the developing device to discharge the collected toner. The toner conveyance relay device is attachably and detachably arranged between the collected toner discharge port of the cleaning device and the collected toner introduction port of the developing device. The destination of the toner discharged from the collected toner discharge opening of the toner conveyance relay device can be switched between the collected toner introduction port and an introduction port of the waste toner bottle by a switching unit.
FIG. 9A is a perspective view of a configuration of a collected toner introduction opening 201 formed in a toner conveyance relay device 200 and that communicates with a collected toner discharge port of a cleaning device, which is not illustrated, to introduce collected toner. The collected toner introduction opening 201 has a rectangular shape opening upward. A flat peripheral portion 202 having a rectangular annular shape is formed on the periphery of the collected toner introduction opening 201. A guide wall 203 composed of three wall surfaces protrudes along three sides of the peripheral portion 202. The collected toner discharge port of the cleaning device, which is not illustrated, is formed on the bottom surface of a connecting unit, which is not illustrated, having an outer shape attachable along the inner wall of the guide wall 203. The collected toner discharge port opens downward so as to be aligned and communicated with the collected toner introduction opening 201. When the connecting unit is coupled to the collected toner introduction opening 201 along the inner wall of the guide wall 203, a flat and rectangular peripheral portion formed on the periphery of the collected toner discharge port is placed opposite and adjacent to the peripheral portion 202 of the collected toner introduction opening 201.
FIG. 9B illustrates a sealing member 210 for preventing toner scattering attached to the collected toner introduction opening 201. The sealing member 210 is manufactured by processing an elastic material, such as a urethane foam, into a plate having a predetermined thickness. The sealing member 210 has an opening 211 having a shape corresponding to the collected toner introduction opening 201. Because the peripheral portion 202 of the collected toner introduction port has a rectangular annular shape, the sealing member 210 also has a rectangular annular shape so as to come into contact with and cover the entire surface of the peripheral portion 202. The sealing member has an adhesive layer on one surface. With downsizing of internal parts and units in response to recent requests for downsizing of equipment, the peripheral portion 202 of the collected toner introduction opening 201 may possibly not be formed into an endless annular shape. As a result, the peripheral portion 202 may possibly have a non-annular shape with a part of the annular peripheral portion cut out, specifically a linear “U”-shape, a “C”-shape, or a “U”-shape, for example.
FIG. 10A is a perspective view of a configuration (no sealing member adheres yet) of the collected toner introduction opening 201 in another toner conveyance relay device. A reference numeral 240 denotes an introduction port that receives new toner supplied from a toner cartridge (new toner container), which is not illustrated. The introduction port is positioned so as to communicate with a collected toner introduction port (new toner introduction port) of the developing device, which is not illustrated, positioned below the introduction port. The peripheral portion 202 of the collected toner introduction opening 201 has a non-annular shape by cutting out a part of the annular peripheral portion, and a cut-out 204 is closed with a vertical wall surface 205. The requests for downsizing prevent the peripheral portion serving as space to which the sealing member adheres from having an annular large area. As a result, the peripheral portion has a non-annular small area as illustrated in FIG. 10A.
As illustrated in FIG. 10B depicting a state where a first and a second sealing members adhere, a first sealing member 220 is attached to the non-annular peripheral portion 202 and includes an elastic member 221 and a flexible sheet material 223. The elastic member 221 is made of a non-annular (linear “U”-shaped) urethane foam (sponge) having a cut-out 221a corresponding to the shape of the peripheral portion 202. The sheet material 223 is made of a material (e.g., polyethylene terephthalate (PET)) harder than that of the elastic member and is attached and adheres to the top surface of the elastic member 221. The sheet material 223 includes a non-annular (linear “U”-shaped) portion 223a, a first protrusion 223b, and a second protrusion 223c. The portion 223a adheres to the top surface of the elastic member 221, and the first protrusion 223b and the second protrusion 223c protrude from the portion 223a. The sheet material 223 covers the elastic member 221, thereby reinforcing it. The sheet material 223 is used to prevent damage caused by abrasion with the connecting unit of the cleaning device attached to and detached from the collected toner introduction opening 201 and to smoothly attach and detach the connecting unit. The first protrusion 223b and the second protrusion 223c cover the surfaces of the elastic member other than the top surface as illustrated in FIG. 10B. Thus, the first protrusion 223b and the second protrusion 223c prevent an end of the elastic member from being turned up when the toner conveyance relay device 200 is attached to a photoconductor, cleaning, and developing unit (PCDU). Both ends 221b of the cut-out 221a of the elastic member 221 are in contact with a vertical wall surface 205 or a second sealing member 230. The toner conveyance relay device 200 is moved in the arrow direction illustrated in FIG. 10B, thereby being attached to the PCDU serving as an integrated unit of the photoconductor, the cleaning device, the charging unit, and the developing device.
FIG. 11 is a view for explaining a configuration of the second sealing member alone. The second sealing member 230 is arranged in a manner adhering to the vertical wall surface 205 adjacent to the first opening 201. The second sealing member 230 cooperates with both ends 221b of the cut-out of the first sealing member 220, thereby exerting a sealing effect. Specifically, the second sealing member 230 prevents leakage of toner falling from the connecting unit (having the collected toner discharge port on the bottom surface) of the cleaning device, which is not illustrated, attached to the collected toner introduction opening 201. As illustrated in FIGS. 10B and 11, the second sealing member 230 includes a plate-shaped elastic member 231 and a flexible sheet material 232. The elastic member 231 is made of a urethane foam or the like and is laterally arranged so as to include a portion facing both ends 221b of the first sealing member 220. The sheet material 232 is made of a material harder than that of the elastic member and adheres to the surface of the elastic member 231. The elastic member 231 adheres to cover the vertical wall surface 205 from a wall surface portion with which both ends 221b of the elastic member 221 are in contact and to a corner 205a. 
The sheet material 232 includes a portion 232a and a protrusion 232b. The portion 232a adheres to the front surface of the elastic member 231, and the protrusion 232b protrudes from an end 232a-1 of the portion 232a. The end 231a-1 of the elastic member 231 ends before the corner 205a of the wall surface 205, whereas the protrusion 232b of the sheet material protrudes beyond the corner 205a. The protrusion 232b is bent toward a second wall surface 205b adjacent to the corner 205a and adheres to the wall surface 205b. The protrusion 232b covers the end 231a-1 of the elastic member 231. Thus, the protrusion 232b can prevent the end 231a-1 of the elastic member 231 from being turned up by direct contact of the end 231a-1 with the photoconductor developing unit (PCDU) when the toner conveyance relay device 200 is attached to and detached from the PCDU along the attachment direction illustrated in FIG. 10A.
The protrusion 232b of the sheet material covers the end 231a-1 of the elastic member 231, thereby preventing the end from being turned up. With this configuration, however, the end 231a-1 of the elastic member 231 is crushed because the protrusion 231b is bent (curved or crooked) to adhere to the second wall surface 205b as illustrated in FIGS. 10B and 12. If the end 231a-1 is crushed, a gap is generated between the end 231a-1 and one of the ends 221b of the first sealing member 221 as illustrated in FIG. 12, resulting in insufficient sealing. The problem described above occurs not only in the joint between the collected toner discharge port of the cleaning device and the collected toner introduction opening of the toner conveyance relay device but also in any joint provided to the path through which the new toner and the collected toner are conveyed. Specifically, the problem also occurs in a joint between the toner conveyance relay device and the developing device, a joint between the toner conveyance relay device and the waste toner bottle, and a joint between the new toner cartridge and the toner conveyance relay device, for example.
Japanese Patent Application Laid-open No. 2001-201926 discloses a developer storing vessel that can reduce contamination caused by scattering of toner in replacement, increase the sealability of the toner vessel, and reduce the volume of the toner vessel, thereby achieving high recoverability and recyclability. The developer storing vessel has an opening used to discharge a powder developer stored inside thereof. The opening is covered with a plurality of sealing members having a slit through which an inserting member used to discharge the developer is inserted and pulled out. The position of the slit varies on each sealing member. The sealing member disclosed in Japanese Patent Application Laid-open No. 2001-201926, however, cannot be applied to the sealing portion in the conventional example in the first place. Thus, it is impossible to solve the defect of crush of the elastic member caused by bending the sheet material and the defect of generation of a gap between the first and the second elastic members.
In view of the above, there is a need to solve a defect of reduced sealability caused by crush of an elastic member included in a sealing member that prevents leakage of toner when two members each having an opening through which the toner passes are connected and the sealing member is arranged. There is also a need to solve a defect of reduced sealability between a first sealing member and a second sealing member caused by the crush of the elastic member included in the first sealing member in a case where sealing is performed with a combination of two sealing members to address a problem that the sufficient arrangement space for the sealing member cannot be secured due to downsizing of an image forming apparatus.